Punching tool

ABSTRACT

A gel-puncher in the form of an outer pipe having a cutting edge at one end, an inner pipe maintained in stationary engagement relative to the outer pipe during operation of the gel-puncher, and means enabling the passage of gas into the outer pipe and then out of the inner pipe; and a kit of parts comprising at least three pipes from which may be selected two pipes to provide one of at least two gel-punchers as described hereinabove, each of which punches holes of a different size.

llnite States Patent [191 [111 3,863,533 Hum Feb. 4, 1975 PUNCHING TOOL Primary Examiner-J. M. Meister B [75] Inventor zzg fig g g g ggg Hum Attorney Agent, or Firm--Dike, Bronstein, Roberts,

Cushman & Pfund [73] Assignee: The Wellcome Foundations Ltd.,

London, England ABSTRACT [22] Flled: 1973 A gel-puncher in the form of an outer pipe having a [21] Appl. No.: 339,223 cutting edge at one end, an inner pipe maintained in stationary engagement relative to the outer pipe during operation of the gel-puncher, and means enabling 83/100 ggg f gj the passage of gas into the outer pipe and then out of [58] Mei! 24 22 the inner pipe; and a kit of parts comprising at least three pipes from which may be selected two pipes to 83/55 30/358 264/153 156 provide one of at least two gel-punchers as described [56] References Cited hereinabove, each of which punches holes of a differt UNITED STATES PATENTS 2,463,455 3/1949 Dann 83/100 x 3 C|a1ms,4 Drawing Figures I 7 WATER PUMP. f-

FHlZ

1p 1 11 9 ///j V/////{//////////// PATENTEU E 197s SHEET 3 OF 3 PUNCHING TOOL This invention relates to certain new and useful improvements in gel punching tools and in particular to a device for punching wells in gels in a single stage op eration.

Gels are commonly used in the biochemical field as media for the diffusion of biological materials. The gels are frequently used in the form of thin layers of about 1 to 2 mm. thickness on rigid base supports. In the layers indentations are made for the introduction of the experimental materials. The materials diffuse outwards from these indentations, which are usually shaped as wells extending throughout the thickness of the gel.

To obtain satisfactory results in diffusion techniques, it is desirable as far as possible that the wells in the gels should have vertical walls and be of regular and uniform bore.

Conventional methods for producing wells in gels comprise a two-stage operation in which the first stage is the cutting of the outline of the well in the gel so as to define a plug of gel, and the second stage is the removal of the plug of gel.

Most usually the plug of gel is removed by aspiration through the tool used to cut the plug of gel, after cutting of the plug is completed. The main disadvantage of such a mode of operation is that a reduced pressure is set up immediately adjacent the circumference of the plug of gel with the result that there is a tendency for the gel adjacent the plug to be disturbed thereby producing irregular wells and/or displacing the gel from the inert base support. In the latter case the experimental materials will tend to leak out from the wells between the base support and the layer of gel, thereby producing a distorted diffusion pattern.

A device that attempts to overcome some of the abovementioned difficulties associated with the removal of the plug of gel has been disclosed by B. Weeke and .l. P. Thomson in Scand. J. Clin. Lab. lnvest. 22 165-166 (1968). The device of Weeke et al comprises an outer punching pipe having a one end provided with a cutting edge and in close proximity thereto an air inlet, and an inner suction pipe in close contact with the outer pipe rearward of the air inlet but freely spaced between the air inlet and the cutting edge. A biassing spring maintains the inner pipe rearward of the inlet in a cutting position except when the inner pipe is manually urged towards the cutting edge into an aspirating position wherein the inner pipe occludes the air inlet. The cutting and aspirating positions are defined by suitable coengaging stops in the inner and outer pipes. In operation of the Weeke device suction means are connected to a remote end of the inner pipe and the cutting edge of the device forced into the gel, the device being in the cutting position and air entering the inlet thereby avoiding a reduction in pressure at the cutting edge.

Once the cutting of a gel plug is completed, the inner pipe is manually urged into the aspirating position in which air may still enter the inlet but must pass between the inner and outer pipes before passing through the inner pipe. Thus although a reduced pressure is established within the inner pipe thereby causing the gel plug to be aspirated, the reduction in pressure immediately adjacent the cutting edge is minimised. It is apparent, however, that the Weeke device is merely a device for performing the conventional two stage method of cutting holes in gelslt is an object of the present invention to provide for the production of holes in gels as a single operation.

It is also an object of the present invention to provide a device which is capable of producing holes in gels having vertical walls and uniform and regular crosssection, in a single stage operation.

It is another object of the present invention to provide a device of the type stated which is not only rugged in construction. but can be manufactured with-a minimum of moving parts and is therefore extremely economical both as to original cost and subsequent maintenance.

Further objects will become apparent in the following non-limitative description of two devices of the present invention.

ln the accompanying drawings FIG. 1 is a longitudinal section of a device of the present invention;

HO. 2 is a longitudinal elevation of the device of FIG. 1 with a template in use for the cutting of holes in a layer of gel, the template, gel and support being shown in sectional elevation;

FIG. 3 is an exploded side view of another device of the present invention; and

FIG. 4 is a transverse sectional view through the plane identified AA in FIG. 3.

In general the device comprises an outer pipe having a one end which has a cutting edge and having an exter nal diameter of from 1 to 10 mm., an inner pipe coaxially located within said outer pipe, means for maintaining said pipes in stationary engagement relative to each other during operation of said device, said one end of said outer pipe extending a predetermined distance of 0.1 to 5 mm. beyond a one end of said inner pipe, and said inner pipe being substantially freely spaced from said outer pipe thereby affording a free passage between said inner and said outer pipes, means remote from said one end of said outer pipe for allowing passage of a gas into said outer pipe from an external source; said inner pipe having a second end formed for substantially gastight engagement of suction means; and said one end of said inner pipe having a transverse cross-sectional area of from 50 to 95 percent of a transverse cross-sectional area of said one end of said outer pipe. Referring to FIG. 1, the device shown comprises a metal outer pipe 1 having a one end 2 which has a cutting edge 3. A metal inner pipe 4 is coaxially located with said outer pipe and is substantially freely spaced from the outer pipe 1. The outer pipe 1 has a second end 5 which is constricted about the inner pipe 4 and rigidly fixed to said inner pipe 4, for example, the second end 5 is welded or silver soldered to the inner pipe 4.

The outer pipe 1 extends beyond a one end 6 of the inner pipe 4, which end 6 is splayed.

The outer pipe 1 is also provided with a side arm 7 which is remote from the one end 2 of outer pipe 1 and through which side arm 7, gas may enter the outer pipe 1 from an external source such as the atmosphere.

The inner pipe 4 also has a second end 8 which is formed for engagement of suction means, for example, a water pump 9 as shown diagramlatically in FIG. 2.

In FIG. 2 the device of FIG. 1 is shown with a template l0 which is located above alayer of gel ll on a rigid base support 12. the template 10 has a plurality of apertures 13 each having a diameter corresponding to that of the outer pipe 1.

In use of the device the second end 8 of the inner pipe 4 is connected to the water pump 9 which is set in action. The one end 2 of the outer pipe 1 is then driven through the aperture 13 in the template 10 located above gel layer 11, until the cutting edge 3 has passed through the gel layer 11 and contacts the rigid base support 12. As the cutting edge 3 approaches the rigid base support 12 gel located within the one end 2 of the outer pipe 1 is drawn into the splayed one end 6 of the inner pipe 4 and aspirated through the inner pipe 4. Whilst the cutting edge 3 is within the gel layer 11, air continuously enters the side arm 7 from the surrounding atmosphere, passing between the outer and inner pipes, l and 4, and thence into the one end 6 of the inner pipe 4 and out of the second end 8 of the inner pipe 4.

After a few seconds pause the device is withdrawn from the aperture 13 in the template 10 and is immediately ready for use again,

In FIG. 3 is shown an exploded side view of a further embodiment of the present invention comprising a metal outer pipe 14 and a metal inner pipe 15 comprising two co-operating parts 16 and 17. A one part 16 of said inner pipe 15 and said outer pipe 14 each have a one end 18 having a gel cutting edge 19 and a second end 20 having an externally screwthreaded portion 21 and an internally screwthreaded portion 22.

The second part 17 of the inner pipe 15 has a one end 23 having an externally screwthreaded portion 24 and a second end 25 formed for engagement with suction means (not shown).

Each of the externally screwthreaded portions 21 has two diametrically opposed plane faces 26 defining cutaway portions 27 of said externally screwthreaded portions 21 as may also be seen in FIG. 4.

In use of the present embodiment, suction means (not shown) engage the second end 25 of the second part 17 of the inner pipe 15 and the externally screwthreaded portion 24 of the second part 17 engages the internally screwthreaded portion 22 of the one part 16 of the inner pipe 15. The externally screwthreaded portion 21 of the one part 16 of the inner pipe 15 engages the internally screwthreaded portion 22 of the outer pipe 14.

The cutaway portions 27 provide passages 28 defined by the plane faces 26 of the externally screwthreaded portion 21 of the one part 16 of the inner pipe 15 through which passages 28 gas may enter from an external source 29 into the outer pipe 14.

The present embodiment of (of FIGS. 3 and 4) may be used to punch holes in gels in the same way as the embodiment pf FIGS. 1 and 2 is used as described hereinbefore.

What we claim is:

l. A gel puncher comprising an outer pipe having a one end which has a gel cutting having an external diameter of from 1 to 10 millimetres; an inner pipe coaxially located within said outer pipe, said one end of said outer pipe projecting a predetermined distance of from 0.1 to 5 millimetres beyond a one end of said inner pipe; means for maintaining said pipes in stationary engagement relative to each other during operation of said gel puncher; said one end of said inner pipe having a transverse cross-sectional area of from 50 to 95 percent of a transverse cross-sectional area of said one end of said outer pipe; means located in said outer pipe enabling the passage of a gas from an external source into said outer pipe; means located between said inner pipe and said outer pipe enabling the passage of said gas within said outer pipe to said one end of said inner pipe, said means for maintaining said inner and outer pipes in stationary engagement relative to one another during operation of said device comprise an externally screwthreaded portion of said inner pipe, for screwthreaded engagement of an internally screwthreaded portion of said outer pipe, and wherein said outer pipe comprise a passage defined by said screwthreaded por tion of said outer pipe and a depression extending along said screwthreaded portion of said inner pipe.

2. A gel puncher comprising an outer pipe having a one end which has a gel cutting edge having an external diameter of from I to l0 millimetres and a second end having an internally screwthreaded portion; an inner pipe comprising two co-operating parts whereby said parts may be disengaged from one another and one of said parts has a one end co-axially located within said outer pipe, said outer pipe projecting a predetermined distance of from 0.1 to 5 millimetres beyond said one end of said one part, said one end of said one part having a total transverse cross-sectional area of from 50 to percent of a transverse cross-sectional area of said one end of said outer pipe; and said one part of said inner pipe having an externally screwthreaded portion for engagement of said internally screwthreaded portion of said outer pipe; the second of said parts of said inner pipe being formed for engagement of suction means; said externally screwthreaded portion of said one part of said inner pipe having a face defining a cutaway portion, said face and said internally screwthreaded portion of said outer pipe together defining a passage through which gas may pass from an external source into the outer pipe to said one end of said inner pipe.

3. A gel puncher kit of parts comprising at least three pipes each having a gel cutting edge and a second end having an internally screwthreaded portion and an externally screwthreaded portion for screwthreaded engagement of said internally screwthreaded portion of another of said pipes or of an extension pipe formed for engagement of suction means and having an internally screwthreaded portion; each of said pipes having an external diameter of from 0.5 to 10 millimetres, each of said pipes other than a pipe having the largest external diameter, having a total transverse cross-section area of from 50 to 95 percent of the internal cross-sectional area of another of said pipes, and each of said pipes having a length such that when said pipe is in screwthreaded engagement with another of said pipes, said one end of the outer one of said pipes projects 0.5 to 5 millimetres beyond said one end of the inner one of said pipes in screwthreaded engagement and each of said externally screwthreaded portioins having a face defining a cut-away portion so that when two of said pipes are assembled said face of the inner of said two pipes and said internally screwthreaded portion of the outer of said two pipes, together define a passage through which gas may pass from an external source into said outer of said two pipes. 

1. A gel puncher comprising an outer pipe having a one end which has a gel cutting having an external diameter of from 1 to 10 millimetres; an inner pipe co-axially located within said outer pipe, said one end of said outer pipe projecting a predetermined distance of from 0.1 to 5 millimetres beyond a one end of said inner pipe; means for maintaining said pipes in stationary engagement relative to each other during operation of said gel puncher; said one end of said inner pipe having a transverse cross-sectional area of from 50 to 95 percent of a transverse cross-sectional area of said one end of said outer pipe; means located in said outer pipe enabling the passage of a gas from an external source into said outer pipe; means located between said inner pipe and said outer pipe enabling the passage of said gas within said outer pipe to said one end of said inner pipe, said means for maintaining said inner and outer pipes in stationary engagement relative to one another during operation of said device comprise an externally screwthreaded portion of said inner pipe, for screwthreaded engagement of an internally screwthreaded portion of said outer pipe, and wherein said outer pipe comprise a passage defined by said screwthreaded portion of said outer pipe and a depression extending along said screwthreaded portion of said inner pipe.
 2. A gel puncher comprising an outer pipe having a one end which has a gel cutting edge having an external diameter of from 1 to 10 millimetres and a second end having an internally screwthreaded portion; an inner pipe comprising two co-operating parts whereby said parts may be disengaged from one another and one of said parts has a one end co-axially located within said outer pipe, said outer pipe projecting a predetermined distance of from 0.1 to 5 millimetres beyond said one end of said one part, said one end of said one part having a total transverse cross-sectional area of from 50 to 95 percent of a transverse cross-sectional area of said one end of said outer pipe; and said one part of said inner pipe having an externally screwthreaded portion for engagement of said internally screwthreaded portion of said outer pipe; the second of said parts of said inner pipe being formed for engagement of suction means; said externally screwthreaded portion of said one part of said inner pipe having a face defining a cut-away portion, said face and said internally screwthreaded portion of said outer pipe together defining a passage through which gas may pass from an external source into the outer pipe to said one end of said inner pipe.
 3. A gel puncher kit of parts comprising at least three pipes each having a gel cutting edge and a second end having an internally screwthreaded portion and an externally screwthreaded portion for screwthreaded engagement of said internally screwthreaded portion of another of said pipes or of an extension pipe formed for engagement of suction means and having an internally screwthreaded portion; each of said pipes having an external diameter of from 0.5 to 10 millimetres, each of said pipes other than a pipe having the largest external diameter, having a total transverse cross-section area of from 50 to 95 percent of the internal cross-sectional area of another of said pipes, and each of said pipes having a length such that when said pipe is in screwthreaded engagement with another of said pipes, said one end of the outer one of said pipes projects 0.5 to 5 millimetres beyond said one end of the inner one of said pipes in screwthreaded engagement and each of said externally screwthreaded portioins having a face defining a cut-away portion so that when two of said pipes are assembled said face of the inner of said two pipes and said internally screwthreaded portion of the outer of said two pipes, together define a passage through which gas may pass from an external source into said outer of said two pipes. 